CN1078923A

CN1078923A - Handle the method for separating some element the aqueous solution that produces again from exhausting nuclear fuel

Info

Publication number: CN1078923A
Application number: CN 93102231
Authority: CN
Inventors: M·勒迈尔; J·富斯; A·盖; M·德雷伊; R·肖梅尔; R·谢维洛特
Original assignee: Compagnie Generale des Matieres Nucleaires SA
Current assignee: Orano Demantelement SAS
Priority date: 1992-03-03
Filing date: 1993-03-02
Publication date: 1993-12-01
Also published as: KR930020488A; TW274140B; DE69306281D1; DE69306281T2; CZ29393A3; FR2688336B1; EP0559537B1; EP0559537A1; JPH06123796A; JP3241475B2; FI930921L; FR2688336A1; SK15093A3; US5372794A; FI930921A0; FI930921A7; CA2090812A1

Abstract

本发明涉及从耗尽核燃料再处理水溶液中分离如Nb、Sb、Ce+Pr、锕系元素和元素周期表VIIb和VIII 族元素中至少一种元素的方法。使此水溶液与聚乙烯吡啶聚合物或共聚物的树脂接触和使水溶液与固定了所述元素的树脂分离。树脂具体是交联型聚(乙烯-4-吡啶)粉末和分离元素诸如钌、铑、钯、锝、锰、钴、铁、镍、铈和镨。The present invention relates to the separation of spent nuclear fuel reprocessing aqueous solutions Such as Nb, Sb, Ce+Pr, actinides and periodic table VIIb and VIII Method for at least one element in the family of elements. Make this aqueous solution with polyethylene contacting the resin of the enpyridine polymer or copolymer and allowing the aqueous solution to Sets the resin separation of the elements. The resin is specifically cross-linked poly(b ene-4-pyridine) powder and isolated elements such as ruthenium, rhodium, palladium, technetium, manganese, Cobalt, iron, nickel, cerium and praseodymium.

Description

Handle the method for separating some element the aqueous solution that produces again from exhausting nuclear fuel

The present invention relates to from exhaust nuclear fuel handle again the aqueous solution of generation separate such as Nb, Sb, Ce+Pr, actinides and periodic table VII b family (Mn, Tc, Re) and VIII family (Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pr) method of at least a element in the element.

Particularly, the inventive method be applicable to reclaim lowly wait, in the aqueous phase stream fluid of medium or high radioactive intensity and fission product concentrate and dissolving exhaust these elements in the nuclear fuel solvent soln, the method also is applicable to the decontamination of the outflow liquid of the existing outflow liquid treating stations that salt content is very high.

The irradiation of nuclear fuel produces the fission product that a large amount of atomic weight are 70-160 in power reactor.At various solution that the terminal of nuclear fuel cycle produces with flow out in the liquid and all have fission product.

Low equicohesive radioactivity flows out liquid, promptly for ¹³⁷Cs and ⁹⁰Its total β specific activity of element beyond the Sr is no more than 0.37GBq/M ³(or 10 ^-2Curie/rice ³), generally contain active manganese, antimony, ruthenium, caesium and cobalt.Radioactivity medium or moderate intensity flows out liquid, and its β specific activity is between 0.37-37GBq/m ³(or between 10 ^-2With 1 Curie/rice ³) between, contain for example radioactive manganese, ruthenium, cobalt, caesium, cerium and praseodymium.High equicohesive radioactivity flows out liquid, and its β specific activity is between 37GBq/m ³-1.8TBq/m ³(or between 1 and 50 Curie/rice ³) between, can contain ruthenium, caesium, cerium, praseodymium, niobium and antimony.Medium and high equicohesive radioactivity flows out liquid owing to the existence as Pu, Am and Cm also has 10 ^-5-3 * 10 ^-2Millicurie/liter between radioactivity.

The solvent soln that exhausts nuclear fuel generally is a salpeter solution, contains actinides, many metals and whole basically fission product, particularly ruthenium 106, caesium 137 and 134, antimony 125, europium 154, cerium 144 and praseodymium 144.

From exhausting the salpeter solution of gained after nuclear fuel solvent soln SEPARATION OF URANIUM and the plutonium, i.e. fission product concentrate, it comprises many elements, especially comprises iron, nickel, molybdenum, copper, ruthenium, rhodium and technetium.

Therefore, an object of the present invention is to separate these and flow out some element that exists in liquid or the solution.Specifically as the platinum group metal of palladium, rhodium and ruthenium, they are that valuable element, particularly rhodium are because it can be used as the catalytic converter of auto industry in these elements.Therefore, the method that ruthenium, rhodium and palladium are effectively separated also is noticeable.

Following document has all been described the separation method of these metals, as R.P.Bush at " platinum metal comment " (Platinum Metal Rev., 1991,35,4, pp.202-208; McDuffie is at ORML/TM-6654,1979., Hazelton etc. are at PML-5758-UC-70,1986 and MacCragh, at US-A-3672875.

These known methods are the methods about separate precious metal from flow out liquid or fine sand lysate, comprise the extraction of for example using liquid metals, volatility process for ruthenium, organic solvent extractionprocess for rhodium and palladium, the precipitation method, active carbon adsorption and use the also reducing process or the like of primary resin of amine-borine type.But the program of describing in these documents is not satisfied, because these methods or be difficult to carry out these metals that maybe can not reclaim Sq.

Should point out, at the aqueous solution of handling or flow out in the liquid, the content of Nb to be recycled, Sb and VII b family and VIII family metal, than other element that exists in the solution, as the content of the sodium in the uranium in the solvent soln and plutonium and some aqueous phase stream fluid will be low many.

The present invention relates to particularly and separates the method that is selected from least a element in Nb, Sb, actinides, Ce, Pr and VII b family and the VIII family element, and the advantage of the method is to be easy to carry out and be applicable to various types of outflow liquid, and rate of recovery height.

According to the present invention, separate to be present in and exhaust nuclear fuel and handle again and exist in the obtained aqueous solution, be selected from Nb, Sb, actinides, Ce+Pr and the periodic table method of at least a element in the VII b family and VIII family element, the method comprises to be made the described aqueous solution contact with the hard resin that with vinylpyridine polymer or copolymer is base and makes the described aqueous solution and the resin isolation of fixing a kind of described element at least.

In the method, using with vinylpyridine polymer or copolymer is that the hard resin of base is very favourable, because described resin has good affinity for Nb, Sb, actinides, Ce+Pr and VII b family and VIII family element.And, this resin Heat stability is good, anti-oxidant and can be used for particularly nitric acid medium of acid medium.

Moreover, because when the element that separates reached capacity the efficient step-down of this resin, can water, acid solution such as 0.1-4M HNO ₃Or aqueous slkali such as 0.1M NH ₄OH washs and makes it to regenerate.

Used vinylpyridine polymer for example can be poly--2-(vinylpyridine) or poly--4-(vinylpyridine).

Operable vinylpyridine copolymer for example can be the copolymer of vinylpyridine and divinylbenzene.

According to the present invention, preferably use the poly--4-(vinylpyridine of following formula institute formula):

It can be by divinylbenzene crosslink.

Commercially available this resin generally is an alkaline form, can use in hydrochloric acid (Saline acid) medium with for example following formula form.

A wherein ^-Expression is as NO ^- ₃Or Cl ^-Anion.

Resin generally is Powdered, and the user can select granular size according to its needed function.

Preferably, can use granularity to be the crosslinked polyethylene of 15-60 purpose-4-pyridine.

This resin also is stable up to 260 ℃ under atmospheric pressure, and it can resist the effect of Oxidizing and Reducing Agents, and insensitive to irradiation.As its close rate of caesium 137 sources is that 200 ten thousand rads/hour (2M rad s/h) shone 8 hours 24 minutes, and resin is sex change not.Can detect by elementary analysis: the content of carbon, hydrogen and nitrogen is constant substantially.In addition, detect with infrared spectrum and also not change and the differential colorimetric analysis shows acomia the changing of form outward appearance, its glass transition temperature is change also.Therefore irradiation does not have or does not almost have any influence to poly-(vinylpyridine).Use the favourable part of poly-(vinylpyridine) also to be to change some treatment conditions such as concentration of nitric acid at last and can make it selective certain element with time of contact of solution.

In general, initial condition solution is salpeter solution, and preferably concentration of nitric acid is 10 ^-7-4 mol and with time of contact of hard resin be 1 minute-24 hours.

Resin consumption more specifically depends on the content of element to be extracted.Ordinary circumstance, every premium on currency solution restrains resin with 10-500.

Be implementation the inventive method, the conventional equipment that can utilize the powder thing to contact with liquid, they can be intermittence or continued operation, as fixed bed or fluid bed exchange column.

Usually under room temperature and atmospheric pressure, move, but also can under other pressure and temperature, work in some cases, as being accelerated reaction.

The inventive method is specially adapted to extract ruthenium, rhodium and/or palladium from exhaust the aqueous solution that nuclear fuel handles again.

When more specifically wishing to extract ruthenium, water concentration of nitric acid maximum equals 1 mol, is preferably 10 ^-7Be 10-60 minute the time of contact of-0.1 mol and solution and resin.In the aqueous solution, introduce hydrogen ion and can quicken to extract dynamics.

When more specifically wishing to extract rhodium and palladium, aqueous solution concentration of nitric acid was preferably the time of contact of 1-2 mol and solution and resin less than 10 minutes.

Prove that as preceding the inventive method can be used for handling and exhausts the various types of outflow liquid and the aqueous solution that nuclear fuel is handled again.

Therefore, the inventive method can be used for separating ruthenium, niobium, calcium halophosphate activated by antimony andmanganese, cobalt, cerium, praseodymium, plutonium, curium and americium from the outflow liquid of medium or high radioactive intensity; Also can be used for from the fission product concentrate, separating Fe, Ni, Rh, Ru, Co and Tc and from the rradiated nuclear fuel solution body, separate Pd, Ru, Rh, Tc, Co, Ni, Fe.

Also describe the present invention in conjunction with the accompanying drawings in detail below by non-limiting example.

Fig. 1 illustrates the variation of the recovery rate (%) of ruthenium with water original solution pH.

Fig. 2-5 illustration as the percentage of the reextraction element of the function of handling effluent volume.

In whole examples, all use about 60 purposes of granularity crosslinked poly--the 4-(vinylpyridine) powder.

Example 1: the separation of ruthenium

Use the inventive method to handle to contain the aqueous phase stream fluid of the nitric acid that ruthenium that concentration is 0.49 mg/litre and concentration is 1.38 mol in this example.

Flow out ruthenium in liquid for extracting this, under magnetic stirrer, make 40 milliliters and flow out liquid and gather-the 4-(vinylpyridine with 1 gram) (PVP) resin contact 30 minutes.On filter paper, separate the PVP resin, remaining ruthenium is measured the recovery rate of dosage and definite ruthenium in the solution with a Plasma2000 type PERKIN ELMER plasma torch (plasma torch), recovery rate is 85%, is equivalent to every gram PVP resin and fixes 0.02 milligram ruthenium.Therefore, the recovery rate of ruthenium is felt quite pleased.

Example 2: the separation of ruthenium

In this example, ruthenium is to extract from the aqueous phase stream fluid of high salinity, and this flows out liquid and contains 1.38 mol HNO ₃, 2 grams per liter Na ⁺, 6 mg/litre K ⁺Ruthenium with 1 mg/litre.

For separating, 1 gram is gathered-the 4-(vinylpyridine) contact 20.5 hours with 40 milliliters of aqueous solution that contain 1 mg/litre ruthenium.Make solution and resin isolation on filter paper, ruthenium remaining in the solution is measured dosage with plasma torch.The recovery rate of measuring ruthenium is 66.5%, is equivalent to every gram resin and fixes 2.66 * 10 ^-2The milligram ruthenium.

Sodium in the filter liquor and potassium shown that quantitatively they are not by resin adsorption.

Example 3: the separation of ruthenium

Undertaken by example 2 identical operations programs, the composition that flows out liquid is identical, and just ruthenium content is 0.3 mg/litre.Stirred 20.5 hours under such condition, the extraction rate reached 100% of ruthenium is equivalent to every gram resin and fixes 1.2 * 10 ^-2The milligram ruthenium.

Therefore, if even the content height of very low and sodium of the content of ruthenium and potassium uses polyvinyl pyridine also can obtain 100% recovery rate of ruthenium.

The separation of example 4 rutheniums

Contain the nitric acid of 1.38 mol, the ruthenium of 0.5 mg/litre, the sodium of 2 grams per liters and the potassium of 6 mg/litre from the aqueous solution that wherein extracts ruthenium, adding sodium chloride again, to make sodium chloride concentration be 1 mol.

Under agitation make 2.5 gram polyvinyl pyridines contact 90 minutes with 100 ml solns, magnetic agitation speed 750r.p.m.On filter paper, separate the PVP resin then and measure the content of remaining ruthenium in the solution with plasma torch.

This operation is used respectively and is carried out

repetition

3,8 and 24.25 hour time of contact, and the gained result gives at table 1.

Table 1

Time of contact (hour) recovery rate (%)

0 0

1.5 68.5

3 68.5

24.25 2

From then on the result can reach high extraction as can be seen after 1.5 hours.But work as Cl ^-When ion does not exist, must wait 8 hours for making resin begin to extract ruthenium.Therefore the existence of chlorion is favourable, because it quickens the extraction of ruthenium.

The separation of example 5 rutheniums

Ruthenium is to separate from the outflow liquid that contains sodium and potassium and studied the influence of pH to recovery rate in this example.For this reason, 10 ml water solution are gathered-the 4-(vinylpyridine with about 0.2 gram) under agitation contact 1 hour, this aqueous solution contains the potassium of trace Ru, 6 mg/litre and the sodium and the nitric acid of 2 grams per liters, and its concentration is equivalent to pH between 3-9.Then, telling ruthenium remaining in PVP resin and the solution on filter paper measures with plasma gun.

Accompanying drawing show the recovery rate of ruthenium and on every gram resin fixing ruthenium amount as the function of pH value of solution.As can be seen: when the pH value is lower than 6, promptly concentration of nitric acid is higher than 10 ^-6Ruthenium is extracted with high efficiency more during mol.

The separation of example 6-9 rhodium

In these examples, be to rub/rise and extract rhodium the aqueous solution of rhodium and concentration of nitric acid as shown in table 2 from containing 2 millis of having an appointment.

0.2 gram is gathered-the 4-(vinylpyridine) (PVP) contact 24 hours to finish extraction with 10 ml water solution, then, filtering solution absorbs with atom then and measures rhodium remaining in the solution to tell the PVP resin on filter paper.The result gives at table 2.

Table 2

The heavy every gram resin of instance number nitric acid recovery rate resin is to the fixed amount of Rh

(mol) be (gram) (milligram/gram) (%)

6 0.7 20 0.23 1.3

7 1.38 30 0.19 3.2

8 2.8 9 0.28 0.66

9 4.2 2 0.23 0.17

The result shows: rhodium fixing not good on PVP when the acidity of medium is too high.Observe maximum extracted during in the 1-2 mol at concentration of nitric acid.

The separation of example 10-13 rhodium

These examples are undertaken by the operation sequence of example 6-9, but use the polyvinyl pyridine of varying number and the aqueous solution to contain 2 millis to rub/liter rhodium and the nitric acid of 1.38 mol.The consumption of polyvinyl pyridine and gained result give at table 3.

Table 3

The every gram resin of instance number polyvinyl pyridine recovery rate is to the fixed amount of Rh

(grams per liter) be (milligram/gram) (%)

10 10 26 5.50

11 20 30 3.20

12 30 34 2.4

13 40 40 2.14

The result shows that recovery rate increases with the consumption of polyvinyl pyridine.

The separation of example 14-16 palladium

In these examples, be to extract the palladium that exists in the aqueous solution, the aqueous solution contains about 1 milli and rubs/liter palladium and the nitric acid of 1.38 mol.Making 10 milliliters of above-mentioned aqueous solution and concentration under level stirs is that the polyvinyl pyridine of 2-40 grams per liter contacts 24 hours.On filter paper, separate polyvinyl pyridine and the palladium atomic absorption detecting that residues in the solution.The consumption of polyvinyl pyridine and gained result give at table 4.

Table 4

The every gram resin of instance number PVP concentration Pd initial concentration recovery rate is right

(grams per liter) (mg/litre) be the fixed amount of Pd (%)

(mg/litre)

14 2 91 100 45.5

15 10 86 100 8.6

16 40 86 100 2.1

The result shows: PVP concentration is at the 2-40 grams per liter, and palladium is easy to extract extraction rate reached 100%.

Above-mentioned example gained result proof is suitably selected acidity, time of contact and resin demand and the suitable ion such as the Cl of adding of initial aqueous solution ^-, can optionally extract ruthenium, rhodium or palladium.

The separation of example 17 rutheniums

This example is to flow out the liquid from high radioactivity to extract ruthenium, and this concentration of nitric acid that flows out liquid is 0.6 mol and also contains caesium-137 and caesium-134 except that ruthenium.Under mechanical agitation, make 3 milliliters and flow out liquid and 200 milligrams of poly--4-(vinylpyridines) (PVP) contact 75 minutes, to finish extraction.Filtration makes resin separate with filtrate, the content of ruthenium and caesium in the mensuration filtrate.The content of ruthenium and caesium is given in table 5 in gained result and the initial soln.

Table 5

Ru106 Cs137 Cs134 salt content (H+)

(comprising 90%NaNO)

Initial soln

(mg/litre) 1.14 * 10 ^-21.43 2.86 * 10 ^-2367 grams per liter 0.6M

After the decontamination

(mg/litre) 4.59 * 10 ^-31.32 2.64 * 10 ^-2

Recovery rate

(%) 59.7 7.7 7.6

Fix 1.02 * 10 ^-41.63 * 10 ^-33.24 * 10 ^-5

(mg/litre)

The result shows in the table: polyvinyl pyridine can be effectively fixing ruthenium 106, because of its extraction rate reached 60%, this is equivalent to every gram resin and fixes 1.02 * 10 ^-4The milligram ruthenium.But, if being flowed out liquid, low-activity carries out identical processing, decontamination is just little effective, because soil removal efficiency increases with the radioactive intensity of initial soln.

Example 18-23 ruthenium, manganese and cobalt separate #S

In these examples, under agitation make 3 milliliters of medium-activities flow out liquid (MA) and contact 40 minutes with polyvinyl pyridine with the different amounts of 2% divinylbenzene crosslink.The composition of MA is given at table 6.The acidity of MA is 0.1 mol.After the contact, polyvinyl pyridine separates with outflow liquid and measures and tell the concentration that flows out ruthenium, manganese, cobalt, caesium and cerium+praseodymium 144 in the liquid.The result gives at table 6.

Table 6

¹⁰⁶Ru ⁵⁴Mn ⁶⁰Co ¹³⁴Cs ¹³⁷Cs ¹⁴⁴Ce+ ¹⁴⁴Pr

After the processing

MA flows out liquid 1.3 0.021 0.13 0.23 8.9 0.23

MBq/l

(MBq/1) (0.036) (0.0057) (0.0035) (0.0062) (0.24) (6.2×10 ^-3)

Recovery rate (%)

(milligram) ¹⁰⁶Ru ⁵⁴Mn ⁶⁰Co ¹³⁴Cs ¹³⁷Cs ¹⁴⁴Ce+ ¹⁴⁴Pr

18 10 2.8 0 0 0 0 12.9

19 50 55.6 0 0 0 0 25.8

20 75 61.1 12.3 48.6 3 0 29

21 100 77.5 14 71.4 2 0 100

22 200 86.7 44 95.4 5 0 100

23 500 87.8 84.2 100 0 0 100

These table data show, can flow out from medium-activity and effectively remove ruthenium, manganese, cobalt, cerium and praseodymium the liquid, but caesium is not extracted.

The extraction of example 24 rutheniums, niobium and antimony

In this example, be to extract ruthenium, niobium and antimony from the height that contains nitric acid is released fluid (HA), it is formed and concentration of nitric acid is given at table 7.

For extracting ruthenium, 50 gram resins are contacted with 1 up-flow fluid, stirred simultaneously 30 minutes, then filtration makes resin separate with outflow liquid, measures the content of ruthenium, antimony, caesium and niobium in the filtrate.The result gives at table 7.

Table 7

⁹⁵Nb ¹⁰⁶Ru ¹²⁵Sb ¹³⁷Cs ¹³⁴Cs

Radioactivity MBq/l 1.6 137 20 115 22 before handling

(mci/l) (0.043) (3.7) (0.54) (3.1) (0.6)

Initial HNO3 concentration recovery rate %

Mol

0 0 0 0 0 0

0.89 100 93 43 0 0

0.7 47 31 31 0 0

0.9 53 35 26 0 0

1.3 44 39 33 0 0

1.9 1 6 4 0 0

As seen from the table, (this be equivalent to height release the standard concentration of nitric acid of fluid) can obtain ruthenium and the very high soil removal efficiency of cobalt when the concentration of initial solution nitric acid is 0.089 mol.

The separation of example 25 rutheniums

In this example, the composition that concentrates from the mat evaporation is extracted ruthenium the outflow liquid of table 8.For this reason, make 200 milligrams of polyvinyl pyridines contact 75 minutes with 3 milliliters of outflow liquid.Isolated by filtration polyvinyl pyridine and measure to flow out the content of ruthenium and caesium in the liquid then.The result provides table 8.

Table 8

[HNO]=0.6M

Amount of resin=200 milligram ¹⁰⁶Ru- ¹³⁷Cs ¹³⁴Cs

Time of contact=75 minute

Flow out liquid radioactivity 1.4 4.8 1.37 before handling

GBq/l(mCi/l) (38) (130) (37)

Recovery rate (%) 56 00

As seen from the table, the recovery rate of the Ru of gained is felt quite pleased.

Example 26: the separating of technetium, ruthenium, rhodium, iron, nickel and cobalt

In this example, from the fission product concentrate that contains many elements, extract technetium, ruthenium, rhodium, iron, nickel and cobalt.This concentrate is the solution from the uranium that exhausts the nuclear fuel lysate, plutonium, the first separating cycle gained.

For this reason, under mechanical agitation, make 2 milliliters of concentrates contact 4 hours 15 minutes with 1 gram polyvinyl pyridine (PVP) with 5 minutes order.

Filter for the first time and tell polyvinyl pyridine, with 18 milliliters of IN HNO3 washings, and then filter for the second time and tell resin, heating for dissolving is in 15 milliliters of sulfuric acid.Analyze solution and the resin dissolves liquid that filters gained for the first time with gamma ray spectrometer, alpha spectrometer and atomic absorption spectrum (ICP).

Gained is the result show: Na, Cs, Mg, Sr, Ba, Cd, B, Al, La, Pr, Ce, Gd, Sm, Eu, Am, Cm and Np are not extracted by PVP with this understanding, but uranium can extract 20% VII b family's metal and the VIII family metal of extracting just as shown in table 9 below.

Table 9

The metal that extracts

The Tc of VII B family

Recovery rate (%) 98 ± 1 (*)

The Fe Ni Rh Ru Co of VIII family

Recovery rate (%) 57 ± 1 (*) 95 ± 1 (*) 97 ± 1 (*) 88 ± 9 (*) 55

(*) standard deviation of three experimental calculation

This resin has good recovery rate to technetium, ruthenium, rhodium, iron, nickel and cobalt, also has good selectivity simultaneously concerning alkali metal, alkaline-earth metal and actinides.

Table 10 provides the distribution (% weight) of metal cation on fission product concentrate and PVP resin.

Table 10

The distribution %(weight of metal cation)

Fe Ni Rh Ru Tc summation

In the FP concentrate 4.2 0.91 0.42 1.7 0.79 8.51

Be fixed on PVP last 37 14.4 6.4 26.5 12.4 100

The bright polyvinyl pyridine that uses of this illness that has not attacked the vital organs of the human body separates VII b family and VIII family metal.Resin can be dissolved in H as needs ₂SO ₄In, and in the aqueous solution, reclaim fixing cation.

Separating of example 27 technetiums, ruthenium, rhodium, palladium, iron and nickel

In this example, from the irradiation lysate, extract technetium, ruthenium, rhodium, palladium, iron and nickel.Under mechanical agitation, make 1 gram polyvinyl pyridine contact 75 minutes with 10 milliliters of lysates.After the contact, filter for the first time and tell resin and, measure the wherein content of palladium, ruthenium, rhodium, technetium, nickel and iron with gamma ray spectrometer and atomic absorption spectrum (ICP) analytical solution.

The resin that separates is with 18 milliliters of 1NHNO ₃Washing then separates resin filter again and is dissolved in 5 milliliters of concentrated sulfuric acids.With γ-spectrometer and atomic absorption spectroscopy lysate.The result gives at table 11.

Table 11

Pd Ru Rh Tc Ni Fe

The composition of lysate

(mg/litre) 334 240 121 3.4 4.9 72

Metal fixed rate (%) 94 65 65 100 92 89

As seen this table is very high for the recovery rate of palladium, ruthenium, rhodium and technetium, particularly technetium and palladium.

Following table 12 provides the percentage and the distribution of reclaiming metal

Table 12

Metal is reclaimed in metal PVP dissolving back in the element solution composition lysate

The distribution (%) of (mg/litre) metal is reclaimed metal (%) and is distributed

U 360000 99.6 9·10 ^-50.95

Pu 1030 0.28 0.3 10.9

Pd 30.5 0.0084 41 18.7

Ru 73 0.020 15 16.6

Rh 27.7 0.0077 30 12.7

Tc 30 0.0083 25.3 11.5

Ni 9.9 0.0027 12 1.8

Fe 111.5 0.031 10.8 18

This table provides and has reclaimed 25% technetium, 41% palladium, 15% ruthenium and 30% rhodium.Therefore can wash a part off with the nitric acid washing resin extracts metal altogether.

Decontamination factor to uranium is 1.1 * 10 ^-6, be 317 and to the decontamination factor of plutonium for the decontamination factor 874 of γ radiation (from Ru106), this feels quite pleased.

Preceding two examples prove: the polyvinyl pyridine resin does not extract trivalent metal, does not extract alkali metal and alkaline-earth metal yet, does not extract or only extract transuranic element seldom, but to extracting very high to transition metal.

When salt content increases, the validity variation of resin.Therefore for lysate, salt content near 200 grams per liters and under this operating condition the exchange capacity of polyvinyl pyridine resin as follows respectively: 3.1 milligrams of Pd/ gram resins, 0.8 milligram of Rh/ gram resin, 1.6 milligrams of Ru/ gram resins and be higher than 0.034 milligram of Tc/ gram resin.

For the fission product concentrate, salt content is near 100 grams per liters and the exchange capacity of resin is respectively as follows with this understanding: 0.7 milligram of Rh/ gram resin, 3 milligrams of Ru/ gram resins and 1.4 milligrams of Tc/ gram resins.

Therefore, can concentrate and exhaust separate precious metal Ru, Rh, Pd and Tc the nuclear fuel lysate from fission product.Also can select the optimal fixation condition and wash the decontamination that the resin that has adsorbed improves these metals.As separate with volatility process Ru,, then as with the aqueous solution of tributyl phosphate washing enrichment, to remove remaining trace plutonium and uranium.

Example 28 medium-activities flow out the decontamination of liquid

In this example, make 3 milliliters consist of table 13 given concentration of nitric acid be 5 * 10 ^-3The polyvinyl pyridine (200 milligrams) that the medium-activity of mol flows out liquid and 67 grams per liters under agitation contacts 30 minutes.After from flow out liquid, telling polyvinyl pyridine, measure the concentration of plutonium, americium, curium and fission product in the outflow liquid of this separation.The gained result gives at table 13.The result shows: polyvinyl pyridine has extracted a large amount of alpha emitters and a large amount of fission products except that caesium and strontium.

Table 13

Element concentrate milli concentrate flows out liquid recovery rate % in the least

Grams per liter grams per liter MBq/ liter

Total Pu 7·10 ^-4>93.8

238Pu 2·10 ^-5>98.8

241Am 8·10 ^-5>98.8

242Cm 1·10 ^-8>90.9

244Cm 1·10 ^-6>96.1

In the gross-fission-product

1.5688 72.5

144Co 0.1517 100

106Ru 0.814 57.3

137Cs 0.2516 5.9

60Co 0.3589 78.4

54Mn 0.0925 93.6

85Sr 0.0444 8.3

Example 29 medium-activities flow out the decontamination of liquid

In this example, be to carry out decontamination to having to the fluid of releasing in the composition in table 14, operation sequence is as described below.

Table 14

Concentration of component

Mg/litre millicurie/rise mol

HNO ₃0.005

Mg 5

K 10

Co 14

Na 6000

U 5

60Co 1·10 ^-2

106Ru 2.3·10 ^-2

134Cs 7·10 ^-4

137Cs 7·10 ^-4

155Eu 2·10 ^-4

144C.+144Pr 9·10 ^-3

Pu 8.6·10 ^-4

244Cm 2.7·10 ^-7

242Cm 2.9·10 ^-9

241Am 2.1·10 ^-5

Make circulation in the pillar that flows out liquid to remove internal diameter be 0.8 centimetre, is equipped with 1 gram polyvinyl pyridine (being equivalent to 4.7 centimetres high), under low pressure in the top of post supply flow fluid with use measuring pump to transport liquid with the speed of 3 ml/min.At the outflow liquid of the bottom of post collection and treatment with by the wherein contained element of assay determination.When there is the weight of element in mensuration, use atomic emission spectrum, when measuring the radioactive element of gamma radiator, use γ-spectrometer and when measuring the radioactive element of alpha radiation body, use α-spectrometer.

The result is illustrated in Fig. 2 and Fig. 3.

Fig. 2 shows the function of the gamma radiator percentage (Ru106, Co60, Ce+Pr144 and Cs137) of extraction as the effluent volume of handling (milliliter).Fig. 3 shows the function of the alpha emitter percentage (total Pu, Am241 and Cm244) of extraction as the effluent volume of handling (milliliter).

These figure show that the percentage that extracts also is very high when the volume of the outflow liquid of handling reaches 360 milliliters/gram polyvinyl pyridine.

After fixing for the first time,, circulated in the opposite direction in the used side of it and processing outflow liquid with also passing through pillar in the bottom introducing post of speed via post of 30 ml waters with 3 ml/min.Then, in this post, under aforesaid the same terms, handle the amount of the element that exists in the outflow liquid of other outflow liquid and mensuration processing.

Fig. 4 shows the function of the effluent volume (milliliter) of percentage (Ru106, Co60, Ce+Pr144 and Cs137) the conduct processing of extracting γ-radiant body element.Fig. 5 provides the function of the alpha radiation body percentage (total Pu, Am241 and Cm244) of extraction as the effluent volume of handling (milliliter).

These figure show that the efficient of this post is well once more, just keep good efficient as hope, and the volume of the outflow liquid of processing is lower.For operation for the second time, described volume is that every gram PVP210 milliliter flows out liquid.

Therefore, the radioactivity of handling the gamma activity element with polyvinyl pyridine be 0.654 millicurie/liter and acidity be that the outflow liquid of 0.005M can be fixed 60% ruthenium and 100% Pu, Am, Cm and Ce+Pr.

Example 30-34 medium-activity flows out the decontamination of liquid

In these examples, various wash solutions have been studied to the influence of PVP regeneration with to the anti-influence of extracting of Ru, Cs, Co, Mn, Ce+Pr, Sr and Pu in the wash solution.In these examples, give at table 15 for these different elements being carried out extract the amount of using polyvinyl pyridine for the first time.Make outflow liquid under agitation contact 30 minutes with PVP.Be determined at the amount of element of fixing during extracting for the first time.The result gives at table 15, is to represent with the percentage that flows out the amount that exists in the liquid.

After extracting for the first time, PVP H ₂O, 0.1MNH ₄OH, 0.1MNH ₄OH+0.1M NaClO, 0.1MHNO ₃Or 4M HNO ₃Washing uses the amount of wash solution will make it with corresponding to PVP concentration in the cleaning solution of table 15.Then measure the content of Ru in the wash solution, Cs, Co, Mn, Ce+Pr, Sr and Pu.

The result of gained also gives in table 15, represents with the percentage of fixed amount on PVP.This result shows that most of elements only instead extract very slightly, removes Cs and Sr exception, and this two element is extracted by PVP hardly.

After washing, Xi Di polyvinyl pyridine is used to handle the outflow liquid of other medium-activity like this, still with identical contact 30 minutes with use the PVP concentration that provides in the amount that flows out liquid and the table 15 corresponding.Then measure and handle the content that flows out Ru, Cs, Co, Mn, Ce+Pr, Sr and Pu in the liquid.The gained result gives in table 15 to extract percentage.

The result shows that the solution of all washings all is effectively, though the only counter very slightly element of fixing when extracting for the first time that is extracted in.At PVP HNO ₃After the regeneration, its extraction efficiency is still higher, and this is owing to use 0.1M HNO new before fixing ₃The efficient of PVP is improved.

Claims

1. A method for separating at least one element selected from the group consisting of Nb, Sb, Ce, Pr, actinides and elements of Group VIIb and Group VIII of the periodic table present in an aqueous solution, the aqueous solution being recycled from exhausted nuclear fuel Treatment, characterized in that the method consists of bringing said aqueous solution into contact with a solid resin based on a vinylpyridine polymer or copolymer, and separating the resin immobilizing the element or elements from said aqueous solution.

2. Process according to claim 1, characterized in that the resin is polyethylene 4-pyridine crosslinked with divinylbenzene.

3. Process according to claim 1, characterized in that the aqueous solution is a nitric acid solution.

4. A method according to claim 3, characterized in that the aqueous solution has a nitric acid concentration of 10 ^-4 -4 mol/liter.

5. A process according to any one of claims 1-4, characterized in that the contact time of the aqueous solution with the solid resin is from 1 minute to 24 hours.

6. Process according to any one of claims 1-5, characterized in that the amount of resin used is 500 g/l of aqueous solution.

7. A process according to any one of claims 1-3, characterized in that the Group VIII element is ruthenium.

8. Process according to claim 7, characterized in that the aqueous solution has a nitric acid concentration at least equal to 1 mol/l and a contact time between 10 and 60 minutes.

9. A method according to claim 7, characterized in that ^Cl- ions are added to the aqueous solution.

10. Process according to any one of claims 1-3, characterized in that the group VIII element is rhodium and/or palladium.

11. Process according to claim 10, characterized in that the nitric acid concentration of the aqueous solution is 1-2 mol/liter and the contact time is less than 10 minutes.

12. The method according to any one of claims 1-3, characterized in that the aqueous solution is a moderately or highly radioactive effluent, and ruthenium, niobium, antimony, manganese, cobalt, cesium, praseodymium, plutonium are separated from said effluent and americium.

13. A process according to any one of claims 1-3, characterized in that the aqueous solution is a concentrate of fission products and that Fe, Ni, Rh, Ru, Co and Tc are separated from this concentrate.

14. A method according to any one of claims 1-3, characterized in that the aqueous solution is a dissolved solution of depleted nuclear fuel and that Pd, Ru, Rh, Tc, Co, Ni and Fe are separated from this solution.

15. A process according to any one of claims 1-14, characterized in that the solid resin is regenerated by contacting it with a washing solution.

16. A method according to claim 15, characterized in that the washing solution is water, 0.1-4M _HNO3 or 0.1M _NH4OH .